Various types of arrangements are known to clamp a grinding disk on a spindle. Usually, an essentially cylindrical coupling element is provided which has a cylindrical reception pin to receive the central hole of a grinding disk. A washer can be tightened against a shoulder on the coupling element by a threaded bolt, inserted into the coupling element. The coupling element, at the other end, is formed with either a tapered bore or a taper pin, which fits, respectively, against a tapered extension of the spindle or into a tapered reception bore of the spindle or another coupling element. An axial bolt connects the respective elements together.
The tapered connection, being a generally cone-shaped connection of very steep cone angle, permits rotation of the grinding disk exactly coaxially with resepct to the axis of the spindle. Yet, the connection is not stiff or resistant against some bending. It has been found difficult to remove the coupling element from the spindle due to the tapered interconnection, since the tapered engagement of bore-and-cone tends to become so tight that an inherent clamping effect, due to the axial tightening of the elements against each other, first must be released. Exchange of grinding disks, therefore, and particularly if grinding disks are to be exchanged automatically in an automatic machine tool, causes difficulty.
It is very important that unintended release of the grinding disk from the spindle be inhibited. Grinding wheels operate at high speed, and safety requires, specifically in machines with automatic tool interchange, that the disk cannot be released from the spindle unintentionally. If a portion or component of the chucking or clamping arrangement should fail, for example due to forces which arise in the operation of the machine, the tool on the automatic machine must not come loose therefrom. In grinding machines, operating at high speeds, this is particularly important.